1. Field of the Invention
This invention relates to a valve for controlling flow of pressurized fluid leading from a confined area and that is operable to relieve an overpressure condition, as well as to allow flow of fluid along the path thereof in response to a pressure relief command. The valve includes a valve body provided with a fluid passage and that is adapted to be mounted in the fluid path. A reverse buckling rupture disc in the valve body is in normal blocking relationship to flow of fluid through the valve passage. The disc, which is oriented such that the convex surface thereof is in facing relationship to the pressurized fluid, is capable of reversing when subjected to a predetermined overpressure condition. A selectively actuatable device carried by the valve body adjacent the convex surface thereof is operable upon actuation to disrupt, without puncturing, the disc to an extent that reversal of the disc is initiated by the pressurized fluid to allow flow of fluid through the valve body passage.
Thus, the valve preferably serves a dual function in which the disc reverses and relieves a predetermined fluid overpressure condition, while at the same time being selectively actuatable to cause the disc to reverse and allow flow of pressurized fluid through the valve body at a selected lower fluid pressure.
2. Description of the Prior Art
Protective overpressure devices, provided with a reverse acting rupture disc having a convex-concavo central section, have long been employed to relieve overpressure conditions existing in vessels and conduits leading from a confined area. The convex face of the rupture disc has been disposed in facing relationship to the fluid pressure. When a predetermined overpressure condition arose, the central section of the disc reversed, thereby opening, and allowing the pressurized fluid to escape from the confined area. One or more knives were provided, in certain instances, adjacent the concave face of the disc to sever the central section of the disc upon reversal in order to assure full opening thereof. A variety of backup components for the ruptured central section of the disc have been mounted in the overpressure device proximal to the concave face of the disc in disposition to be engaged by and minimize separation of the reversed central section of the disc from the peripheral flange portion thereof.
These prior art devices have all been functional to relieve a predetermined overpressure condition, and were not operable to selectively reverse and open at a predetermined fluid overpressure significantly less than the withstand pressure of the central section of the disc.
The prior art is also replete with valves that utilize a shiftable device for penetrating a rupture disc to effect opening thereof and thereby release a pressurized fluid from a confined area. Included are darts or sharpened members that are propelled into engagement and through the disc, as exemplified by the devices in U.S. Pat. Nos. 2,206,818, 2,441,011, 3,134,390, 3,913,604, 3,938,704, 4,566,476, 4,830,052, 5,010,911, 5,076,312, 5,257,819, 6,672,616, 6,748,743, 6,834,885, and 6,938,421. Piston-like members have also been provided that are shiftable into and through a rupture disc to effect bursting thereof. Examples of piston-type actuators are found in U.S. Pat. Nos. 1,671,368, 2,417,082, 3,027,903, 3,101,733, 3,129,716, Re. 29,614, U.S. Pat. Nos. 4,006,780, 4,421,005, 4,542,761, 4,630,682, 5,345,876, 6,234,522, 6,755,439, 7,140,381, 7,143,775, and 7,143,776, and Publication No. US 2006/0137742. Other valves rely upon an explosive charge to effect opening of a rupture disc. Exemplary explosively actuated valves are disclosed in U.S. Pat. Nos. 2,766,832, 3,604,511, 3,811,511, 4,046,156, 4,084,602, 4,263,971, 4,779,683, and 6,240,948.